Berlioz - Hungarian March
Advice
Although this is a staple audition excerpt for trombone, it is one of the most challenging. Many exceptional players see this as their weakest excerpt, so don't feel discouraged if you find it difficult. Listen to all recordings on repeat until you get the correct idea in your head. I like to listen to full low brass section recordings the most for this purpose. Notes should be full value and longer than you think to fit the orchestral style. Pay special attention to the length of the whole note before 4, and make sure your intonation and body of sound on the notes is in check, especially on the octave drops. I recommend recording yourself and listening back to find areas for improvement.
Resources
Full Orchestra Excerpt Recording - London Symphony Orchestra
Breaking Down the Excerpt with Joe Alessi